Shock strut



- April 25, 1939. c, v. HNSON SHOCK STRUT Filed Sept. 26, 1934 g 5 Z. P

VII/Ari IN VEN TOR Carl 1 Jb/uaso/z/ ATTORNEY v ever, that the drawing is Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE Carl V. Johnson, South Bend,

Ben

Ind., assignor to Products Corporation, South Bend, Ind., a corporation of Indiana Application September 26, 1934, Serial No. 745,624 16 Claims. (Cl. 261-04) Accordingly, an object of the invention is to provide a shock strut for heavy duty and quick 1' mounting and demounting in an inverted strut sock A further object of the invention is the provision of a'shock strut adapted to operate in pairs, with the compressed gas chambers, interconm nected.

to minimize turbulence of metered liquid within a the air chamber.

Another object is the provision of a resilient bumper adapted to absorb shock resulting at the end of a compression stroke resulting from unusual landing shocks.

' the greatest pressures by landing shocks.

The above and other objects and novel features when taken in conjunction with the accompanying drawing. It is expressly understood, howemployed for purposes of illustration only and is not designed as a deflnition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein like reference numerals 45 indicate like parts:

Fig. 1 is a longitudinal section of a shock strut constructed in accordance with the novel features of the invention;

Fig. 2 is a transverse section of Fig. 1 taken on 50 the line 2-2 therein; and

Fig. 3 is a longitudinal section of a portion of the shock strut of Fig. v1 showing several modifications.

Fig. 4 diagrammatically illustrates the method 01' pairing struts.

Referring to Fig. 1 of the drawing, it will be seen that the strut comprises generally two parts, an upper or stationary fixed part, and a lower recylindricai or tubular member carrying a packing chamber 22 at its lower end and an oriflced end closure member 24 at its upper 'end.

As illustrated, the end closure member 24 has a cylindrical flange 26 having a threaded portion 21 screwed into the end of the tubular member 20 adjacent the thickened end 28 and radially outing an air compression chamber 33, the upper .end of which latter member 32 is provided with an end closure cap 34. A filler plug 36 and reinforcement 38 therefor is also preferably provided in the side wall; adjacent the cap 34.

Entering the cap as near the top as practicable is a nipple 40 to which is secured a tube 42 which may connect' to an adjacent shock strut, when the same are employed in pairs, so as to equalize the pressures therein.

30 of the cylindrical member 20 and such engagement is eifected by the flanged nut 48 and threaded collar 60 which squeeze the two flanges 46 and 30 togetheraround an intervening alignment or centering collar 62 which may, it desired, be integral with either flange 46 01; 30. Suitable pins such as 64 and 56 which pass through slots in the collar and flange 46 prevent relative rotation between these members while the flanged nut 48 is provided with spanner holes 68 to aid in drawing the flanges 26 and 46 tightly together. be split through the slots to provide two part so that the collar may be placed above the flange 46.

The lower end of the cylindrical member 20 has 1 an oflset portion of greater diameter to house the packing 22, and is threaded exteriorly at the end to receive the end nut 62 having ,a radially inwardly extending flange adapted to retain the packing comprises an acting against annular L", sectioned packing rings 66 and an end collar l0 engaged by the flange of nut 62.

In practice the collar ill may- The packing engages the face of the piston sleeve 88 of the lower reciprocating part, which part is provided at its lower end with a tubular transverse split socket 8| for engaging an axle or axle carrying member for a landing wheel. On the upper end of the sleeve is positioned a piston 82 in the form of a cap having internal threads engaging external threads on the sleeve 88. The piston is secured against loos 84 which are threaded in or cap and pass through apertures provided therefor in the upper end of the sleeve 88.

To regulate the effective area of the orifice 88 heretofore referred to in the end closure member 24 of cylindrical member 28, a metering pin 88 of chosen contour is secured to the piston as shown and is adapted to reciprocate within the orifice 86, the varying contour thereby varying the effective orifice opening. Immediately below the piston 82 and within the piston sleeve 88 is provided a bulkhead or diaphragm 98 which is preferably seated in a slight shoulder 82 on the inner wall of the sleeve, the purpose of the bulkhead being to prevent leakage of liquid past this point from within the strut, it being understood that the strut is partially filled with a hydraulic damping liquid.

As shown in Fig. 3, the piston may be dispensed with and the bulkhead strengthened to carry the metering pin. Such arrangement also provides an annular space between the sleeve 88, bulkhead or diaphragm 98 and pin 88 in which a resilient or rubber doughnut 92 may rest which may in the event of an extreme shock strike the end closure plate 26 to cushion the extreme end of the main shock absorbing stroke. One or more radial pins 84* may pro ect inwardly and provide the dual function of holding the threaded bearing collar 83 in place and engage slots 84 in the doughnut to retain the same. The piston or collar in either modification may have oil grooves such as 98 in Fig. more elemental grooves 98 to allow free passage of fluid therepast to the packing, or both as may be desired.

In order to prevent rebound immediately after the initial landing shock, the end closure member 24 has positioned a short distance above it, a diaphragm I88 which is supported in an annular internal shoulder I82 in the flange reduced diameter portion 3|. The tral orifice I84 smooth exterior surin which is secured a tubular housing member I88 closed at its upper end which serves to enclose the metering pin. Ports I88 in the diaphragm cooperate with an annular valve I I8 slidably mounted around the housing member I88 and the latters movementis limited by an annular collar II2 afiixed to the housing member, a short distance up from the diaphragm I88. One or. more bleed ports I are provided in the diaphragm ata point out from under the valve to permit gradual extension of the strut after a shock, it. being understood that ports I88 are closed by valve I I8 to prevent rebound.

In practice, the strut is filled with liquid above the piston 82 and to a level above the orifice 86 and preferably above the diaphragm I88. The

' further filled with compressed depending on the load carried and the cross section of the strut. The initial shock of landing is absorbed by forcing the damping liquid through the orifice 88 to dissipate the energy and through the open valve ports I88 into the top compres- 'top of said diaphragm,

1, or be provided with one or supporting means diaphragm has a cenand extending into said chamber 1 receive said metering pin, port holes in said valve sion chamber.

ing may be absorbed by compressing the gas in the chamber above that normally required to sustain the load during taxiing. Such compression would cause reboun except that the flap valve II8 closes the ports I88 restricting return flow of the liquid to bleed ports Ill. Upon taking off, the maximum extension of the strut is governed by the engagement of the piston 88 with the sleeve 98 which in turn rests on the packing retaining ring 64, and the rate of extension is re- -vided of novel design adapted for heavy airplane transport use and in pairs, and although but a single embodiment of the invention with varying details has been illustrated and described, it is to be understood that the invention is not limited thereto but may be embodied inother mechanical arrangements and equivalent forms. As many such changes may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claims for a definition of the invention.

What is claimed is:

1. A shock strut comprising a diaphragm member having an orifice and a tubular casing member extending downwardly therefrom, a piston adapted to reciprocate in said tubular casing, a chamber secured on vtop of said diaphragm, and hollow tubing means independent of the strut and extending beyond the upper end of the strut for supporting said strut adjacent said diaphragm.

2. A shock strut comprising a diaphragm member having an orifice, a tubular casing extending downwardly therefrom, a chamber arranged on a piston reciprocable in said casing, and hollow tubular full load supporting means secured to said casing adjacent said diaphragm and extending beyond the end of said chamber.

3. A shock strut comprising a diaphragm member having an orifice, a tubular casing extending downwardly therefrom having a reciprocating piston therein, a chamber extending upwardly and hollow tubular full loadfrom said diaphragm,

for said strut extending beyond the end thereof and secured thereto substantially in the plane of said diaphragm.

4. A shock strut comprising a diaphragm member having a central orifice, a tubular casing extending downwardly therefrom, a chamber above said diaphragm, a piston in said casing carrying a metering pin reciprocable in said orifice, a valve diaphragm above and adjacent said diaphragm and having a central orifice, a housing closed at its upper end secured over said second named orificeand extending into said chamber and adapted to receive said metering pin, port holes in said valve diaphragm, and a valve member slidably mounted on said housing adapted'to close said port holes.

5. A shock strut comprising a diaphragm member having a central or fice, a tubular casing extending downwardly therefrom, a chamber above said diaphragm, a piston in sa'd casing carrying a metering pin reciprocal in said orifice, a valve diaphragm above and adjacent said diaphragm having a central orifice, a' housing closed at its upper end secured over said second named orifice and adapted to diaphragm. a valve, member slidably mounted Some of the initial shock of landon said housing adapted to close said port holes, and a bleed port in said valve diaphragm outside the sphere of action of said valve member.

6. A shock strut comprising a tubular casing, means to support the casing at its upper end, a diaphragm in its upper end having an orifice, a chamber over said orifice independent of said support means, a piston adapted to reciprocate in said casing, a tubular piston rod secured to said piston and emerging from the bottom of said casing, and packing carried in the lower end of said casing coacting with said piston rod.

'7. A shock strut comprising a tubular casing,

adapted to reciprocate in said casing and having a metering pin cooperating with said orifice, a tubular piston rod secured to said piston and emerging from the bottom of said casing, and packing carried in the lower end of said casing coacting with said piston rod.

8. In a shock strut, a tubular support member having at its lower end an outwardly extending flange, a tubular casing member having an outwardly extending flange at its upper end adapted to cooperate with said first named flange, said casing member carrying a main metering orifice member immediately adjacent the upper end,

an outwardly extending member having an outat its upper end adapted flange, a tubular casing wardly extending flange to PO Derate with said having an upwardly extending peripheral flange.

a central orifice therein, means for forcing dampwith said orifice, for said metering aperture.

and a closed tubular housing pin to extend into closing said port diaphragm. w

12. A pair of shock struts eachcomprising a diaphragm member having-a central orifice, a

. preventing ize the pressures therein.

13. A pair of in unison each comprising a diaphragm memher having a central orifice, a chamber above said diaphragm, means for forcing damping liquid through said orifice including a metering pin adapted to reciprocate therein, means closely adjacent said orifice tov prevent rebound, and means pressures therein said diaphragm members having means for rigidly connecting them together and said forcing means having remote from said orifice or rebound means said diaphragm members having means for rigidly connecting them together and said forcing means having means for rigidly connecting them together.

15. In a shock strut, a pair of telescopic tubular members, an orificed diaphragm member carried by one 01' said members, a closure member for the other of said tubular members spaced from the end thereof, said closure member cara metering pin adapted to cooperate with said orificed member, an annular resilient memshock struts adapted to operate I her loosely seated on said closure member around said metering pin adapted to engage said orifice member and resiliently limit relative movement between said member, and radial extending means carried by and adjacent the end of the other of said tubular members extending into side recesses in the resilient member for loosely securing the resilient member in place.

16. A pair of shock struts adapted to operate in unison, each comprising telescopic casings diaphragm carried by the upper casing and a metering pin cooperating with the orifice of said diaphragm and. carried by the lower casing, and means connecting the upper casings together to equalizethe pressures therein, said upper casings having means for rigidly connecting them togetherand said lower casings having means for rigidly connecting them together.

CARL V. JOHNSON. 

